I don't have root access to this server, only access to the Site Admin control panel. I figured this was the best place to post my problem though.

I am having troubles sending email to user[at]mydomain.com. I get a bounce back from my yahoo and my ISP saying:
[ip of site] does not like recipient.
Remote host said: 550 5.7.1 <user@mydomain.com>... Relaying
denied. Please check your mail first or restart your mail session.
Giving up on [ip of site].

However, I can successfully send mail to user[at]www.mydomain.com. That makes me think that something isn't quite right...

I remember when I used to set up new accounts on these machines, there was something 'different' you had to do to set up the mail, but it has been over a year since I did that. (I used to work for the company hosting the site and I am troubleshooting this for a client of theirs).

Also, in the site admin control panel, under services > email I cannot enter an email server alias or email catch-all address, which I found wierd. I also could only enter an email alias for the user under User Management, but maybe that is standard?

Thanks in advance for any help.